The present invention relates to a device for continuous or semi-continuous casting of a metal material, wherein the device comprises a casting mould which allows casting of a metal material to a desired shape, means for supplying a molten metal material to the casting mould, a first arrangement comprising a coil having an extension around the casting mould in a moulding area arranged to comprise molten metal material and which coil is arranged to be fed with an alternating current in such a way that a varying magnetic field is generated and is applied to the molten metal material in the casting mould and a second arrangement comprising at least two magnetic poles which are provided at opposite sides of the casting mould and which poles are arranged to supply a static or periodic low-frequency magnetic field to the molten metal material in the casting mould.
The metal material used at such a casting process may be a pure metal or an alloy of metals. The casting mould usually used is a cold mould, which is open in both ends in the casting direction. The mould has usually a substantially square or rectangular cross-section. Said means are arranged to allow supply of the melt at an open or closed casting. In connection with a continuous casting process for manufacturing of a usually elongated cast strand, it is known to use an arrangement called electromagnetic casting (EMC). The electromagnetic casting implies that one applies a varying magnetic field to the melt in the casting mould. By the presence of the varying magnetic field in the melt, the melt is subjected to a force action, which is directed towards the interior of the casting mould. The contact pressure between the melt and the wall surface of the casting mould decreases and an increased surface fineness of the finished metal material may thus be obtained. In connection with a continuous casting process, it also is known to use another arrangement, which is called electromagnetic brake (EMBR). Such an electromagnetic brake comprises yokes and poles, which are provided around the casting mould. The yokes and the poles are constructed of a solid magnetic steel. Coils are provided around the poles. The coils are arranged to be fed with direct current such that in the air-gap between the poles a static magnetic field is created which is applied to the molten metal material in the casting mould. Such a static magnetic field brakes the motions of the molten material in the casting mould. Hereby the risk decreases that harmful inclusions arise in the finished cast strand in form of, for example, slag and gases.
However, the existence of the solid poles of the magnetic material of the electromagnetic brake in immediate vicinity of the coil fed with alternating current results in an influence of the magnitude and extension of the varying magnetic field. According to calculations, the flux density of the varying magnetic field may decrease with about 23% in the melt at a presence of such solid poles. Furthermore, the solid poles of the electromagnetic brake become subjected to an inductive heating by the varying magnetic field. Therefore, the poles need to be chilled.